1. Field of the Invention
The present invention relates to catheters and more particularly to an inflatable balloon catheter, particularly for use in intra-aortic pumping.
2. Description of the Prior Art
Intra-aortic balloon pumping is a recognized method of cardiac assistance for a failing heart. It is also a recognized method of treating cardiogenic shock and has been used to help wean a patient way from cardiopulmonary bypass, to support a patient during a difficult postoperative period, and to provide a pulsatile flow to the linear flow supplied by the cardiopulmonary bypass device. Intra-aortic balloon pumping has also been used therapeutically after myocardial infarction to limit the extension of necrosis and has been used as a therapy for angina pectoris.
Catheters for intra-aortic balloon pumping presently utilize a nonstressed or nondistensible balloon, i.e., the balloon is not stretched during inflation and never changes its surface area substantially, inflating and deflating with a predetermined volume of appropriate fluid to achieve phasic operation; the balloon surface area is always substantially equal to that of a fully inflated balloon. The intra-aortic balloon catheters of the prior art are relatively stiff and bulky and have a large "entering" cross-section. The femoral artery has heretofore been used for insertion of these stiff and bulky intra-aortic balloon catheters because of the large diameter of that artery. However, considerable surgery must be performed in order to reach and isolate the femoral artery. In addition, a large incision must be made in the femoral artery wall to permit introduction of these prior art devices. The safeness of intra-aortic balloon pumping using the catherters of the prior art has been questioned since they can cause and in some instances have caused aortic dissections, perforations and trauma mainly because of the entering size and the relative stiffness of the devices. Additionally, this stiffness prevents precise maneuverability of the catheter within the vascular structure and thereby limits its potential for efficacy.
It is recognized in the prior art that insertion and guiding of catheters is difficult and that trauma and damage to the incision and blood vessel may occur during said insertion and guiding. The balloon of prior art catheters is commonly rolled or spirally wrapped around its underlying catheter tube in order to insert it into and guide it in a blood vessel. In Grayzel, U.S. Pat. No. 3,939,820, an attempt is made to obtain a tight wrap in which the size of the enclosed catheter tube is decreased by replacing it with a thin support member or wire. The balloon membrane, however, must still be wrapped, or rolled, and the limited amount of balloon material available and the limited magnitude of the torsional stress that may be applied to twist the balloon limit the tightness of the roll regardless of whether the balloon is twisted around a catheter tube or around a thin support member. In catheters of the prior art, the balloon tip and gas supply tube are rigidly connected to each other within the balloon (Goetz, et al., U.S. Pat. No. 3,692,018 and Jones, U.S. Pat. No. 3,504,662), or are rigidly connected to each other by a thin support member within the balloon (Grayzel, U.S. Pat. No. 3,939,820), or are connected to each other within the balloon by a non-twistable, copper current-carrying braid (Kantrowitz, et al., U.S. Pat. No. 3,585,983). The twisting of the balloon about its longitudinal axis is therefore limited since no rotational displacement is possible between the balloon tip rigidly fastened to the distal end of the balloon and the catheter tube or support means rigidly fastened to the proximal end of the balloon.